Hi chet808,
this "Vocal Cancel" feature works reasonably well with just a few files.
The result depends on how a particular Audio file is mixed. In principle, in the method used here, only the signals in the Stereo center (where usually the lead voice is located) are made quieter (by summing up the two Stereo channels "out of phase").
BUT with MOST of the existing Audio songs (MP3s) this method does NOT work well, unfortunately.
Best regards,
Chris